Method for producing resilient cotton fabrics through partial esterification



United States Patent Office 3,432,252 METHOD FOR PRODUCING RESILIENTCOTTON FABRICS THROUGH PARTIAL ESTERIFICATION John B. McKelvey, Ruth R.Benerito, and Ralph J. Berni, New Orleans, La., assignors to the UnitedStates of America as represented by the Secretary of Agriculture NDrawing. Filed Nov. 23, 1965, Ser. No. 509,419 US. Cl. 8-120 8 ClaimsInt. Cl. D06m 13/00, 1/00; C07d 51/18 A non-exclusive, irrevocable,royalty-free license in the invention herein described, for allGovernment purposes, throughout the world, with the power to grantsublicenses for such purposes, is hereby granted to the Government ofthe United States of America.

This invention relates to partial cellulose esters. More particularly,the invention relates to the production of monobasic saturated andunsaturated fatty acid esters of cellulose.

The primary object of the present invention is to provide an improvedprocess for the partial esterification of hydroxyl group-containingcellulosic textile fibers using long-chain alkanoic acid halides withoutaltering the desirable physical properties of the textile fibers andsimultaneously imparting the important properties of resiliency (creaseresistance) and increased elongation. Another object is to providealkanoic and alkenoic esters of cellulose in fabric form by utilizingmonobasic acid chlorides which cannot crosslink the cotton fiber and,consequently, will not alter some of the more desirable physicalproperties of these cellulosic materials. A further object of thisinvention is to produce partial cellulose esters having a degree ofsubstitution (D.S.) of 0.05 to 0.2, having improved resiliency and stillmaintaining their resistance to abrasion.

Methods for the application of fatty acid chlorides to cellulosicmaterial to obtain water repellent surfaces are known in the prior art.In most of these prior art processes, cotton cloth is first treated withsodium hydroxide and then introduced into carbon tetrachloride or otherinert solvents containing an acid chloride. The product obtained is afabric with a soft woolly texture, fatty feel and water repellentcoating but either shows little or no change in, or loses some of itsrecovery properties. Other prior art processes include use of both DMF(dimethylformamide) and pyridine for producing esters of cellulose of DS1, which are products having properties very different from untreatedcotton fabric. Other prior art processes utilizing dimethylformamide andpyridine include treatment of fabric to obtain oil and water repellencyusing perfluoroalkanoyl chlorides. All of those prior art processesproduced textile fabrics which failed in the commercially importantproperty of retain ing their textile characteristics; of improved creaseresistance or resiliency, abrasion resistance, and improved elongation.

We have now discovered an improved esterification process for theproduction of partial alkanoic and alkenoic esters .of cellulosicmaterials having degrees of substitution (D.S.) ranging from about 0.05to 0.2 whereby the treated cellulosic material is not only renderedcrease resistant in the conditioned (dry) and wet states but has theadded advantage of improved elongation-atbreak. The novel esterificationprocess of the present invention does not alter significantly thestrength, color, appearance, hand, or fibrous form of the cellulosicmaterial. This was unexpected.

In general, in accordance with the present invention, a hydroxylgroup-containing cellulosic material is esterified by reacting with thehalide of the esterifying agent of an alkanoic or alkenoic monobasicacid wherein the alkanoyl or alkenoyl radical contains from 8 to 22 car-3,432,252 Patented Mar. 11, 1969 bon atoms. The esterification processof this invention is accomplished by a reaction between the hydroxylgroups of the cellulosic material and one or more of the alkanoyl oralkenoyl esterifying agents, in the presence of dimethylformamidesolvent and a quantity of tertiary aromatic amine sufiicient toneutralize the generated acid reaction products to their respectiveamine salts. The process of the present invention is characterized by acritical sequence of addition of the reactants, and of washing theesterified cellulosic material, which sequences are described below.

Substantially any cellulosic material containing hydroxyl groups cansuitably be employed in the present processes. Illustrative examples ofsuch materials include cellulose derived from cotton, flax, ramie, wood,and the like; regenerated cellulose, such as viscose rayon and the like;partial ethers of cellulose such as partially acetylated cellulose,beta-propiolactone-reacted cellulose, and the like; and partial ethersof cellulose such as carboxymethyl cellulose and other partiallyetherified cellulosic materials. In general, the cellulosic textilematerials in the form of free fibers, slivers, yarns, threads orfabrics, including the fibrous material and partial ethers or partialesters thereof which are produced by reactions in which the fibersretain their cellulosic textile properties, are preferred startingmaterials. The cellulosic textile fibers in the form of spun textiles,i.e., yarns, threads, or fabrics, are particularly suitable startingmaterials.

An alkanoyl or alkenoyl halide of substantially any alkanoic or alkenoicmonobasic acid wherein the alkanoyl radical contains from about 8 to 22carbon atoms can be employed as the esterifying agent in the presentprocess. Acids whose esterifying agents can be employed includecaprylic, nonanoic, capric, undecanoic, lauric, myristic, palmitic,stearic, oleic, linoleic, ricinoleic, petroselenic, erucic acids, andother like acids. Although alkanoyl or alkenoyl halides such as thechlorides, bromides and iodides may be prepared from the commerciallyavailable monobasic acids, we prefer to use the chlorides such as12-hydroxystearoyl chloride. These chlorides may be prepared by theconventional method based on the use of thionyl chloride. Aftercompletion of the reaction the excess thionyl chloride is stripped offand the acid chlorides recovered by distillation at reduced pressures.

In this invention, the solvent plays an important role. It is a criticalfeature of our novel process that only aprotic solvents of highdielectric constant, such as dimethylformamide and dimethylsulfoxide,are capable of disrupting the active hydrogen bonded network incellulose and result in the partial esterification of cellulose withlong-chain fatty acid moieties at the desired sites. In order to attainconditioned (dry) and wet crease resistant (resilient) cellulosicmaterials, the sites of esterification must be at particular C hydroxylsites of cellulose which were originally hydrogen bonded through water.Use of solvents with a low dielectric constant, or solvents not capableof disrupting the original hydrogen bonded network of cellulose, orprotic solvents does not result in cellulosic materials possessing theproperties described in this invention.

In reacting the cellulosic material with the esterifying agent of thealkanoic or alkenoic acid, substantially any apparatus usually employedsuch as a Pyrex cylinder in the esterification of cellulose may be usedin carrying out our novel esterification process. The cellulosicmaterial to be reacted is first thoroughly dried in an oven orappropriate drying apparatus before immersion into the reactionsolution. The acid chloride and dimethylformamide (DMF) are mixed in thereaction vessel and are brought to the desired reaction temperature. Itis usually preferred to employ from about 5 to 40 moles ofdimethylformamide (or dimethyl sulfoxide) for each mole ofanhydroglucose unit of cellulose to insure complete immersion andwetting of the fabric samples. The quantity of acid chloride added isnot critical but it is preferred to use at least an equimolar ratio ofacid chloride to anhydroglucose units. After the reaction mixture isbrought to the desired temperature, which may range from about 25 to 105C., preferably 60 to 105 C., an equimolar quantity of pyridine withrespect to the acid chloride is entered into the reaction vessel. It isanother critical feature of our invention that the pyridine is heated ina separate container to the reaction temperature prior to addition tothe DMF-acid chloride solution. The amount of pyridine is not critical.However, since it is to be used as an acid scavenger, the amount usedwill depend upon the temperatures employed. At low temperatures, 25 C.,less than equimolar quantities can be employed but at temperatures near105 C. greater than equimolar quantities with respect to acid chlorideemployed are necessary to prevent physical damage to the cellulosicmaterial. A preferred range of pyridine quantities would be from 0.16 to4 moles of pyridine for every mole of acid chloride employed. Afteraddition of the pyridine the dried fabric is entered into the reactionmixture, for. the required reaction time or period of dwell. Theaforementioned sequence of addition of reactants is of utmost importanceand must be followed in the esterification process of the presentinvention. It is unsatisfactory, for example, to dissolve theesterifying agent in DMF and pyridine and bring the reaction mixture tothe desired temperature, because the pyridine-acid chloride complexformed will seriously affect the efficiency of the esterification of thecellulose. Most important, it will prevent the attainment of creaserecovery.

The extent of reaction, and thus degree of substitution (i.e., thenumber of the three reactive hydroxyls per an hydroglucose unit whichhave been substituted, by replacing a hydrogen atom with an acylradical, as indicated by the proportion of acyl groups per unit weightof the cellulosic material) can be varied widely.

The degree of substitution can be varied primarily by (a) varying theproportion of esterifying agent in contact with the cellulosic materialduring the esterification reaction and (b) varying time and temperatureof the esterification reaction. In general it is preferable to conductthe esterification reaction at above the crystallization point of thesolution used for the esterification and below the boiling point of thesolution. Reaction temperatures from about room temperature 25 C. toabout 105 C. are preferred. Under the preferred esterificationconditions, resilient (crease resistant in conditioned (dry) and Wetstates) cellulosic materials can be produced using reaction times as lowas 5 minutes at 105 C. or in 8 hours at room temperature. As above, thisresiliency can be realized at extremely low degrees of substitution ofthe cellulose. It is generally preferred to esterify the cellulose to aD5. between 0.05 and 0.20 to impart the aforementioned desirableproperties.

Following completion of the esterification reaction, it is veryimportant that the treated cellulosic material be washed free ofreactant solution before washing the cellulosic material in water. Inthe preferred washing procedure, the treated material is separated fromthe reaction mixture and soaked three times in fresh pyridine in orderto remove any pyridinium salts which may adhere to the fabric. Then thetreated material is steeped three times in boiling methanol and finallyquenched thoroughly in cold running water for at least 30 minutes. Afterwashing, the fabrics are ironed dry or oven dried and then equilibratedat least 16 hours before weighing. If the material is first washed inhot water, the color-forming pyridinium salts will react with thecellulose and cause the final product to have not only a discoloredappearance but also a foul odor.

The folowing examples are illustrative of certain details of theinvention.

Methods of Testing Conditioned Crease Recovery using Monsanto Testeraccording to US. Federal Specification CCC-T-191b- Method 5212-U.S.Federal Supply Service.

Wet Crease Recovery-Lawrence ModificationLawrence, E. W. and Phillips,R. N., Am. Dyestuff Reptr. 45, 548-550 (1956).

Elongation-at-Break and Breaking Strength-A.S.T.M. Methods D3959.

Saponification ValuesEberstadt Titration as described by Genung, L. B.and Mallatt, R. C., Ind. Eng. Chem. Anal. Ed. 13, 369-374 (1941).

Example 1 (Preferred method of treatment) A 10 g. portion containing0.06 mole of anhydroglucose units of x 80 cotton fabric (desized,scoured and bleached) was placed in an oven at C. for 45 minutes. Oleoylchloride (0.06 mole) was dissolved in 2.1 moles ml.) ofdimethylformamide and heated in a graduated cylinder at 105 C. for 45minutes. Simultaneously, 0.25 mole pyridine was heated in a separatecontainer at the same time. The pyridine was then added to DMF-acidchloride mixture and followed by the dried, rolled fabric which wasimmersed below the surface of the reaction mixture. The reactionproceeded for 30 minutes (a period of dwell) after which the fabric wasremoved from the reaction medium and soaked three times in pyridine andthen steeped three times in boiling methanol. The fabric was thenquenched for 45 minutes in cold running water before being ironed dry(at 150 C.). The resultant fabric consisted of alkenoyl (oleoyl) estersof cellulose having a D5. of 0.15 (as indicated by a weight gain of 27%)and a saponification value of 1.588 milliequivalents (meq.) of acylgroups per gram of sample.

The treated fabric had physical properties like those of the originalfabric-that is, its tear strength, color, appearance, hand, and fibrousform were not physically altered by the treatment. It had a MonsantoCrease Recovery Angle (CRA) of 277 (warp-i-fill) when conditioned, and240 (W+F) wet. (Control untreated cotton values are (W+F) conditionedand 150 (W+F) Wet.) The fabric had an elongation of 12.1% as compared to7.9% for the untreated control. The fabric had excellent durability withrespect to resiliency (crease recovery) since after ten home launderingsit still possessed a Monsanto Wash Wear rating of 4.

Example 2 Another portion of the same cotton fabric used in Example 1was treated according to the procedure of Example 1 except that reactiontime was reduced to 5 minutes at 105 C. The resultant fabric had a D5.of .05 (weight gain8.7%) and a conditioned recovery angle of 225 (W+F)and a wet recovery angle of 187 (W+F).

Example 3 The following data are illustrated of the ranges of D.S.,crease recoveries, and elongation that can be obtained.

Other portions of the same cotton fabric were treated according to theprocedure in Example 1 except the reaction times were varied andproducts were obtained as lllustrated 1n the followmg table.

Crease Recovery Elongation Reaction Time D.S at break (minutes)Conditioned Wet (percent) Example 4 The following is illustrative of theother acyl chlorides which can be used to obtain improved creaserecovery and elongation properties.

(e) adding the amine to the solvent solution of the acyl halide to forma reaction solution;

(f) immersing the dried cellulosic material into the reaction solution;

(g) maintaining a period of dwell at a temperature Other portions of thesame cotton fabric were treated 5 f to f hrs. to 5 minutes; aflcorfilngto the p f P 1eXcl tthatTeac (h) removing tertiary aromatic amine saltsfrom the tion tunes and the acid chlorlde used were varled, and thetreated f b i b ki h f b i t l a t three results obtained are shown inthe following table: times in fresh pyridine;

R ti T 11 E eac on e Acid Chloride time ecovery iii-k (min.) Cond. Wet(percent) Caprylic 180 00 0.10 200 212 9.5 Nonarioic 180 60 0. 13 213202 9. 0 aprlc 180 60 0.09 223 206 9. 1 Undeceno 105 0. 17 239 220 13. 0auric-.- 180 00 0.15 223 213 8.1 45 105 0.09 222 204 8.9 180 60 0.12 234209 8.1 120 00 0.12 249 221 9.0 15 105 0.13 243 191 12.5 00 105 0.14 257239 10.9 00 105 0.19 307 295 9.7 90 105 0.16 284 293 10.5 60 105 0.19251 238 15.7 12-hydroxystearic. 60 105 0. 19 274 263 13. 3 Phenylundecanoic 12 105 0.13 243 221 9.2 Acetylated Rieinoleic 60 105 0.08 270247 10.5 oz-Bromostearic 50 105 0. 09 237 209 10. 0 Petroselenic... 5060 0. 09 241 206 8. 2 Control (80x80) 195 150 7.9

Example 5 3 (i) removing the solution of reactants by steeping the Thefollowing example is illustrative of partial esterifi- 0 fabr1c threetlmes' 111 sh lllng methanol; cation carried out according to Example 10f USP. (I) th roughly Washing the treated fabric in cold runl,897,026to illustrate that the products formed do not mng Water for 30 mmutes;possess improved conditioned and wet recovery. (k) f and equlhbratmg thetreated Cenuloslc Sixteen parts by weight of the same cotton fabric usedmaterlaliapd in Example 1 are first immersed in a 20 percent aqueous (l)determlnlng the degree of substltution of the dried caustic sodasolution, thereupon pressed free of excess and equlhbrated f causticsolution, and are then introduced into carbon tetramethod as F F clam 1Wperem the chloride in which there has previously been dissolved 28aProtlc Solvent of dlelectrlc constant 18 ,Selected parts by weight ofacid chloride mixture obtained by 40 frfml the 2 2 conslstmg ofdlmethylformamlde and treatment of commercial stcarin (80% stearicacid-20% dl'methylsulfoxlde and ranges f about 5 to 40 moles palmiticacid with thionyl chloride and which, therefore, to one m anhydroglucoseof cellulose consists principally of the chlorides of palmitic andstearic method as flescrlbed Glam 2 Y f the acids. The cotton fabricremains for one hour in the CC1 aprotlc solvent of hlgh dlelectncconstant dlmethyl' solution, which was expediently heated to 35-55 C.formamlde- The fabric that had been treated in this manner pos- A met11das desqlbed 1n clalm Whetem the y sesses, with undiminished strength, afatty feel, has a soft hallde 1S Pf P from a Selected from h woollytexture and is diflicult to moisten with water. How- P P alkanolc andalkenolc monobaslc ever, the conditioned and wet recovery obtained was138 aclds and 1S Pf m at least one mole P mole anhy" and 166 (W-l-F)respectively. Control values are 195 drogluwse mm of cellulPsepr/+1?conditioned and 150 (W+F) wet 5. A method as described 1n claim 1wherein the halide It will be observed that when the fabric is treatedwith is a chloride NaOH prior to reacting with the chlorides of palmitic6 A method as described 1n 01am 1 wherein the and stearic acid, thetreated fabric loses its elasticity and ternary aromatlc amlne 1S py 111an its wet and dry crease recovery. Most important it loses ing fromab011tO-16 1110195 to P mole aftld ha11dethe physical properties of theoriginal fabric, i.e., tear A methPd as descnbed m clalm 1 Wherem thestrength, h l d appearance gree of substitution (D.S.) of the celluloseranges from We claim: 0.05 to 0.2.

1. A method for increasing the resiliency and elonga- T Product P p ythe PmceSs as descrlbed tion of cellulosic textile materials by partialesterifica- In clal'm tion without crosslinking the anhydroglucosemolecules comprising the following steps in sequence: References Cited Ydrymg h cellulosls f McKelvey et al.: Textile Research Journal vol. 34,pp.

(b) charglng to a reaction vessel an aprotlc solvent 11024104 1 4) ofhlgh fhelectflc constant and an acyl hahde sald McKelvey et al.: TextileResearch Journal, vol. 35, acyl halide being prepared from at least onei'nem- 365476 5 her of the group consisting of alkanoic and al-kenoicmonobasic acids and contaln ng from about 8 to 22 NORMAN G. TORCHIN,Primary carbon atoms 1n the acyl chain, (c) bringing the solvent and theacyl halide to reac- CANNON Asslstam Exammertion temperature, (d) in aseparate container bringing a tertiary aromatic amine to reactiontemperature,

US. Cl. X.R.

1. A METHOD FOR INCREASING THE RESILIENCY AND ELONGATION OF CELLULOSICTEXTILE MATERIALS BY PARTIAL ESTERIFICATION WITHOUT CROSSLINKING THEANHYDROGLUCOSE MOLECUSES COMPRISING THE FOLLOWING STEPS IN SEQUENCE: (A)THROROUGHLY DRYING THE CELLULOSIS MATERIAL, (B) CHARGEING TO A REACTIONVESSEL AN APROTIC SOLVENT OF HIGH DIELECTRIC CONSTANT AND AN ACYLHALIDE, SAID ACYL HALIDE BEING PREPARED FROM AT LEAST ONE MEMBER OF THEGROUP CONSISTING OF ALKANOIC AND ALKENOIC MONOBASIC ACIDS AND CONTAININGFROM ABOUT 8 TO 22 CARBON ATOMS IN THE ACYL CHAIN, (C) BRINGING THESSOLVENT AND THE ACYL HALIDE TO REACTION TEMPERATURE, (D) IN A SEPARATECONTAINER BRINGING A TERTIARY AROMATIC AMINE TO REACTION TEMPERATURE,(E) ADDING THE AMINE TO THE SOLVENT SOLUTION OF THE ACYL HALIDE TO FORMA REACTION SOLUTION; (F) IMMERSING THE DRIED CELLULOSIC MATERIAL INTOTHE REACTION SOLUTION; (G) MAINTAINING A PERIOD OF DWELL AT ATEMPERATURE OF 25* TO 105* FOR 8 HRS. TO 5 MINUTES; (H) REMOVINGTERTIARY AROMATIC AMINE SALTS FROM THE TREATED FABRIC BY SOAKING THEFABRIC AT LEAST THREE TIMES IN FRESH PYRIDINE; (I) REMOVING THE SOLUTIONOF REACTANTS BY STEEPING THE FABRIC THREE TIMESS IN FRESH BOILINGMETHANOL; (J) THOROUGHLY WASHING THE TREATED FABRIC IN COLD RUNNINGWATER FOR AT LEAST 30 MINUTES; (K) DRYING AND EQUILIBRATING THE REATEDCELLULOSIC MATERIAL; AND (L) DETERMINING THE DEGREEE OF SUBSTITUTION OFTHE DRIED AND EQUILIBRATED FABRIC.